The present invention relates to a method for routing calls from a terminal in a first telecommunication network, for example an intranet, to any terminal in an external telecommunication network, the interworking between said networks taking place through one of several interworking units or so-called gateways.
Problem Intranets
Intranets can exceed country borders, and in fact many corporate networks are covering nearly the whole world. The cost of communicating within an intranet is usually much lower than using external communication services, and the intranets usually do not see the country borders. This means that the cost of communicating within an intranet is less dependant on the geographical distance between the endpoints and more on initial investment in network infrastructure. This is in sharp contrast to the charging involved when using commercial telephone services, where distance and duration of call more directly determines the cost of a call.
New emerging standards within video and audio conferencing now make it possible to have audio and video conferences/calls within PSTN (ISDN) networks, the Internet, Intranets and Local Area Networks.
Since other network domains now support making audio and video conferences/calls, the need for ways of interworking between these different kind of networks has emerged. These interworking units are called gateways, and they provide the conversions necessary (protocol, audio format, video format etc.) for endpoint/terminals residing in different kinds of networks, to be able to communicate with each other.
There are no limitations on the number of gateways which can be connected to these networks, which means that an intranet can have access to several gateways in order for a terminal inside the intranet to call e.g. an ISDN video conferencing terminal.
Because of cost issues it would be desirable for example to establish a connection through the gateway residing closest to the receiving party on e.g. the PSTN or ISDN network. For example, since an intranet can cross country borders it could be desirable to place one gateway in each country and avoid expensive international calls by always calling out through the gateway residing in the country where the receiving party is located.
Known solutions and problems with these
Related problems have probably been solved for circuit-switched (telephony) networks, where routing tables assure that distributed companies with local telephone networks route as much as possible of each call within the local network before entering the public telephony network. This should apply to packet networks (intranets, LANs etc.) as well, but routing tables must with this solution be entered manually. This invention proposes inter alia a way for a dynamic generation of routing tables for audiovisual communication when going from packet-networks to other networks (circuit- and packet networks) via gateways by the automatic update of routing information from gateways to the routing entities within the packet network.
An object of the invention is to provide a method whereby such routing of calls can be affected in a generally most optimal manner.
Another object of the invention is to provide a method wherein such routing may be affected in the most cost effective manner.
Still another object of the present invention is to provide wherein such routing may be affected in the most resource effective manner.
Yet another object of the invention is to provide a method selection of network operators may be made in an effective manner.
An object of the invention is also to provide a combined optimalization of such routing and selection.
These objects are achieved by a method as stated in the preamble, which according to the present invention is characterized in that there is used at least one routing entity which routes the call or calls through a gateway (GW1, GW2) giving the most optimal route, for example the most cost effective or resource effective route.
In other words, the invention proposes inter alia to automatically route interworking calls (i.e. over gateways) from packet-networks through the gateway giving the most cost effective charge by using a routing table which is automatically updated each time a new gateway is introduced into the network.
Reference in this invention proposal is done for example towards an emerging ITU standard H.323 for IP based video/audio/data conferencing, but the invention should apply equally to packet networks in which registering functions are available and calls to other networks are available (e.g. Internet, Intranet telephony, voice over IP, etc.).
In a specific embodiment of the invention the key approach is for the routing entity (from now on referred to as gatekeeper, logical switch, when referring to audio-visual communication on packet networks) to know which gateways exist, and in what country or region they are connected to the public telephony network. When the gatekeeper knows this, it can for example analyse parts of the E.164 number (given to the gatekeeper by the caller residing inside the packet-network/intranet upon initiation of an interworking call) for the receiving party outside the intranet in order to route the call to the most appropriate gateway. In this way as much as possible of the call propagates within the packet-network/intranet and that the most local gateway to the receiving party (charging wise) is selected for putting the call out on the public telephony network.
Further features and advantages will appear from the following description taken in connection with enclosed drawings, as well as from the appending patent claims.